Bar pilots, like the one guiding the Cosco Busan when it struck an abutment of the Bay Bridge last week, take responsibility for thousands of passengers, huge cargoes worth billions of dollars, thousands of passengers and for the welfare of people, structures and ecosystems around the Bay.
The 60 members of the San Francisco Bar Pilots Association use their local expertise to guide nearly every ship that enters the Bay past its unique sand bars, submerged rocks and other hazards.
With that liability comes generous rewards and political clout unmatched in other regulated trades.
Last year, the average pilot's income was $491,892.
Pilots divide among themselves the fees paid by shipping companies, which came to $29.7 million, after subtracting $11.2 million in expenses.
The state has given the association the power to submit drug and alcohol tests to its members, a practice that seemed to confuse Coast Guard officials investigating Wednesday's bridge collision. The accident only superficially damaged the bridge, but it resulted in the Bay's worst oil spill in a decade.
While investigators still don't know the cause of the accident that opened a 100-foot-long, 12-foot-wide gash in the ship's side, tearing open two fuel-oil tanks, much of their attention undoubtedly will be focused on the pilot, 59-year-old John Cota of Petaluma.
"These are very big ships, and they don't handle like a little sports car," said Jim Buckley, professor of maritime transportation at the California Maritime Academy in Vallejo. Pilots "have to be mentally ahead of the ship, they have to be anticipating things ... because something that's 70,000 tons doesn't respond very quickly."
Pilots are part of the state's oldest regulated association. In 1850, in its very first session, the Legislature established the Board of Pilot Commissioners for the Bays of San Francisco, San Pablo and Suisun. Its seven governor-appointed members now regulate the 60 association members.
The board, which consists of two members each from shipping companies and the pilot association and three public members, licenses pilots, tests their proficiency and contracts with schools from the Bay Area to Grenoble, France, to train them, said Capt. Patrick Moloney, the board's executive director and one of two staff members.
The board also provides oversight and investigates accidents. Wednesday's accident was the fifth this year, Moloney said.
But maritime sources said the pilots and their association often are at odds with the shippers they serve as a state-sanctioned monopoly.
In 2003, a state court ruled that shippers could refuse a pilot assigned by the association if it was dissatisfied with that individual, a right the association refused to grant.
The profession has become "much more open in the last 30 or 40 years; it's become much more democratic" and much easier to break in to after a past rife with nepotism, said Tim Lynch, maritime history professor at the academy.
Moloney said pilots are vital to shipping, frequently risking their lives as they board ships in rough seas at the prescribed 11 miles outside the Bay.
"In the past two years nationally, we lost five pilots and a pilot boat crew member," from accidents such as falling off the ladder while climbing up the sides of huge ships, or drowning when pilot boats capsize in rough seas.
On Friday, the Coast Guard released a few details of its investigation, which is focused on communications between the pilot and three crew members on the bridge of the ship, and at least one lookout stationed on the bow, the lead investigator, Ross Wheatley, said.
The crew members -- the master of the Cosco Busan, the officer of the deck and the helmsman -- were Chinese, although some communicate regularly in English, Wheatley said.
The pilot appeared to be trying to navigate between towers D and E, the two just west of Yerba Buena Island, said Capt. David Swatland, deputy commander of the San Francisco Coast Guard Station.
The water between those three bridge towers is deep enough so that any course through the 2,310-gap between them would be safe, but Buckley said the bridge has its own peculiarities.
"When you get close to the piers on that bridge, you get into some interesting current situations," which can push or pull a vessel astray, Buckley said.
Modern technology has made it easier than ever to maintain course with radar used in conjunction with electronic charts that employ global positioning to show a ship's real-time location and its relationship to obstacles in the area.
Staff writer Bill Brand contributed to this story. Reach Erik Nelson at email@example.com.